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F.28

Flame signal not detected during ignition

F.28 means the boiler did not detect a flame signal during the ignition phase.

What this code means

F.28 means the boiler did not detect a flame signal during the ignition phase.

Possible causes

  • Insufficient or interrupted gas supply
  • Frozen or blocked condensate pipe
  • Ignition electrode fault
  • PCB fault
  • Flue-system issue

Common symptoms

  • Boiler fails to ignite
  • No heating or hot water
  • F.28 displayed

Checks to make

  1. Check whether other gas appliances are working
  2. Check that a pre-payment gas meter has credit if applicable
  3. In freezing weather, safely check any external condensate pipe for freezing
  4. If the simple external checks do not resolve it, arrange a qualified engineer

Safety

  • Do not remove the boiler casing or work on the gas, ignition, combustion or flue system yourself. If you smell gas, leave the property and follow the gas emergency procedure.

Model notes

Vaillant describes F.28 as failure to detect flame during ignition.